The developers of the former Retro Studios unveiled concept drawings for two of Nintendo's canceled titles. According to reports, the two games are an unfinished "The Legend of Zelda" game and a game project called "Haunt" with Kingboo as the protagonist.
You can see that the style of this Zelda game is dark, and it is said that this game is an action JRPG featuring Sheik. And this project with Kingboo as the protagonist seems to be built for the handheld.
Unfortunately, both games have been cancelled. Hopefully, Retro Studios can bring us the new Metroid sooner rather than later.